As is generally known, plastic bottles can be already be labeled in the course of the production process through so-called in-mold labeling (IML) by introducing the labels in the blow mold before blow molding is executed. To this end, the label is positioned by means of grippers on the inner wall of the opened blow mold, as described in U.S. Pat. No. 6,649,119 B2, U.S. Pat. No. 5,266,149 A and WO 00 785 26 A1 for rotary blow molders. Transfer star wheels with grippers are, however, technically complicated. Non-rotating, clocked transfer systems do not achieve the manufacturing efficiency demanded. In addition, there is a need for a device that can easily be integrated in existing blow molder such that it takes up little space.
Hence, US 2002/0166833 A1 and DE 2135406 A suggest as an alternative that sleeve-shaped labels should be pushed onto or shrunk onto a preform, and DE 198 06 647 A1 additionally suggests that a flat label section should be applied to the preform by winding and transferred to a blow molding carousel via a transfer star wheel. In the case of these methods the label is, however, substantially stretched together with the preform and the suitability of these methods for lettered labels is therefore very limited.
Furthermore, EP 0098351 A2 and U.S. Pat. No. 4,708,630 A disclose blow molders in which flat labels are fixed, at the outlet of an extruder, to an unfinished bottle by pressing them onto the just extruded, still plastically deformable sleeve of the unfinished bottle. This method is, however, not suitable for use with preforms prefabricated by injection molding.
The introduction of self-gluing labels into the blow mold with the aid of a carrier strip conducted through or along the blow mold is known e.g. from CH 509864 A and DE 1479083 A; the labels can here be separated from the carrier strip by punching them out or by removing them at a peel-off edge. This solution, however, limits the design flexibility as regards mold construction and bottle design, it causes problems when the carrier strips are being exchanged, and it is inflexible and technically complicated, since separate supply units are required for the individual blow molds.
The labeling of bottles with the aid of print heads integrated in the blow molds is described e.g. in DE 1479322 A1, U.S. Pat. No. 2,601,700 A or U.S. Pat. No. 3,438,085 A. However, this solution is not suitable for all kinds of bottle designs either. It is also disadvantageous insofar as at least one print head is required for each blow mold, printing qualities and/or printing formats are restricted, and the dyes must be handled at the blow molder.